Effective Grounding Analysis of a Non-Wires BESS Alternative in a Remote Distribution Feeder

Power system resilience begins with the basics of continuity of supply in cases of long and widespread outages. In Puerto Rico, residents are well used to major events that are in theory low probability but have happened a few times in the past few years. One way to address these deficiencies in remote areas is to employ non-wires alternatives that have lower adoption capital cost as compared to a conventional (poles and wires) solution. Energy storage is a means to achieve this objective. Technical needs of such solutions require analysis and can degrade system performance. One of such cases is effective grounding. To supply distribution-connected unbalanced load, the solution requires to be a source of ground and at the same time, this source of ground cannot be too strong as not to desensitize the feeder protection, which is predominantly overcurrent based. It is a fine balance between establishing a ground source and ensuring operation of ground overcurrent protection. This paper presents a case study of a project being planned by the Puerto Rican transmission and distribution system operator and highlights the importance of these solutions and the need for adequate technical assessments and implementation with all the correct components.